Integrated coal conversion process

ABSTRACT

An integrated process for the conversion of coal to liquid and gaseous fuels is disclosed. Coal and oil are hydrocracked in the presence of a particulate maxture of sand or clay and an iron and chromium alloy to form carbon-coated sand and an overhead product comprising cracked oil vapors and fuel gases. The carbon is removed from the sand to form carbon monoxide with the concomitant generation of heat. The carbon monoxide is used to reduce oxidized iron and chromium alloy located in a hydrogen generating bed. Steam is passed into the bed of reduced metallic alloy to form hydrogen for use in the coal reactor and the regenerated particulate mixture of sand and iron and chromium alloy is returned to the coal reactor, to continue the sequence of carbon removal and to provide heat for the hydrocracking reaction.

This is a division of application Ser. No. 858,045, filed Dec. 6, 1977now U.S. Pat. No. 4,132,627 filed Nov. 2, 1979.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a method of producing primarilygasoline and fuel gas when processing coal in the presence ofsuperheated steam and fluidized sand. Carbon deposited on the sand isremoved by oxidation to provide heat for coal conversion and carbonmonoxide for regeneration of a metal reagent hydrogen generator. In thehydrogen generator, which preferably comprises a fixed bed ofiron-chromium alloy, carbon monoxide produced by removal of carbon fromthe sand is passed up through the bed reducing the alloy to the activemetal/metallic form and steam is thereafter passed downwardly throughthe bed to form, hydrogen for use in the coal reactor. Distillate dieseloil separated from the coal reactor overhead may be hydrogenated andused for coal extraction prior to recycling along with coal to the coalreactor. A variety of process schemes downstream of the coal reactor maybe utilized to remove sulfur, carbon dioxide and coal ash and to recoverand/or recycle selected fractions of hydrocarbons from the coal reactoroverhead product.

2. Description of the Prior Art

In the prior art the conversion of coal to marketable fuels hasgenerally required substantial purchased or onsite oxygen often costingas much as the coal being processed. Also in the coal conversionprocesses of the prior art, carbon dioxide formation generallyaccompanied hydrogen production necessitating expensive carbon dioxideremoval procedures. Moreover, where hydrogen production was generated bythe interaction of iron and steam according to the Messerchmidt processand others, generally the iron had a tendency to to sinter andagglomerate decreasing the surface area of the iron and, therefore,drastically reducing the activity thereof.

The present invention provides for the use of a bed of iron and chromiumalloy for hydrogen generation in order to ameliorate the problem ofagglomeration. Also, in accordance with the present invention, theforegoing mode of hydrogen production is integrated with a coal reactionutilizing an admixture of sand and an iron and chromium alloy in orderto remove and utilize carbon from the coal reactor to intermittentlyregenerate the bed of alloy and to provide heat for sustaining the coalconversion process.

BRIEF SUMMARY OF THE INVENTION

The invention relates to a method of converting coal to liquid andgaseous fuels which comprises hydrocracking a coal and oil mixture in acoal reactor in the presence of hydrogen and in the presence of aparticulate mixture of sand and iron and chromium alloy to form a spentparticulate mixture of sand having a carbon-coating thereon, a spentiron and chromium alloy, coal ash and an overhead product comprisingcracked oil vapors and fuel gases. The particulate mixture comprisingcarbon-coated sand and the spent iron and chromium alloy is withdrawnfrom said coal reactor and the carbon coating is removed from the sandin the presence of an oxygen-containing gas to form carbon monoxide anda regenerated particulate mixture of sand and regenerated iron andchromium alloy. The carbon monoxide is passed into a bed comprising aparticulate oxidized second iron and chromium alloy and the particulateoxidized second alloy is reduced to metallic form. Steam is passed intothe bed of said second metallic alloy to form hydrogen and at least aportion of the hydrogen is passed into the coal reactor to effecthydrocracking therein. The regenerated mixture of sand and first ironand chromium alloy is passed into the coal reactor as the mixture ofsand and first iron and chromium alloy therein. The first and the secondiron and chromium alloys contain from about 5% to about 30% chromium andthe particulate mixture of sand and first iron and chromium alloycontains about 10% by weight alloy.

An excess of steam is preferably introduced into the particulate secondiron and chromium alloy to form a product stream comprising hydrogen andexcess steam, and the product stream is thereafter introduced into thecoal reactor to provide at least a portion of the hydrogen and steamrequirement therefor.

The particulate bed of second iron and chromium alloy is preferably afixed bed.

The spent particulate mixture of sand having a coating of carbon thereonand the first iron and chromium alloy is preferably oxidized in afluidized bed to form carbon monoxide. The carbon monoxide is passedupwardly into a fixed bed of oxidized second iron and chromium alloy toreduce the alloy. Steam is thereafter passed downwardly through theresultant reduced second iron and chromium alloy to form a product gascontaining hydrogen, and the product gas is thereafter introduced intothe coal reactor to provide hydrogen for effecting hydrocrackingtherein. Hydrogen production is preferably effected utilizing an excessof steam which is passed downwardly through the reduced second iron andchromium alloy to form a product gas containing hydrogen and excesssteam. The product is thereafter introduced directly to the coal reactorto provide at least a portion of the steam and hydrogen requirementstherefor.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic illustration of the invention.

DETAILED DESCRIPTION OF THE INVENTION

Having thus described the invention in brief general terms, reference isnow made to the schematic drawings in order to provide a betterunderstanding of the present invention.

It is to be understood that the drawings are shown only in such detailsas are necessary for an understanding of the invention and that variousitems such as valves, bleed and dispersion steam lines, instrumentationand other process equipment and control means have been omittedtherefrom for the sake of simplicity. Referring to the drawing, coal isfed into lock-bins 2 and 3. The coal may be dried in the lock bins withhot recycle gas introduced through line 4. The water removed from thecoal is withdrawn via line 5.

Where non-caking coal is employed, the coal may be augered directly vialine 7 to coal reactor 10. In the bottom portion of reactor 10 arelocated a dense phase of sand 11 which operates as a seal to preventvapors from exiting from the bottom of reactor 10 and a dilute fluidizedsand phase 12 which is superimposed over the dense phase of sand 11. Thenon-caking coal is introduced into dilute sand phase 12.

Where caking-type coal is employed, the dried coal is preferably augeredvia line 6 to coal-oil extractor tower 8 and introduced into oil layer 9located in the bottom portion of extractor tower 8. A coal-oil slurry isformed and is pumped via line 54 to coal reactor 10 and introduced intodilute sand phase 12.

The moisture content of the coal on a weight percent basis shouldpreferably be from about 1% to about 50% and most preferably from about10% to about 30%. Upon contact of coal with the fluidized bed of sand orclay the transformation of the moisture to steam effects disintegrationof coal particles.

Ash formed within reactor 10 is blown upwardly through central duct 13into settling zone 16, settling into ash accumulator 14. The ash iswithdrawn from accumulator 14 via line 15 and passed to ash decarbonizer82. Steam may be injected via line 19 into ash accumulator 14.

At the top of coal reactor 10 a steam generator 17 or equivalent may beemployed in order to cool the overhead comprising oil vapors, fuel gasand excess steam prior to passage thereof via line 18 into coal oilextractor 8.

Superheated hydrogen generally at a temperature of from about 1000° F.to about 1800° F. and excess steam from hydrogen generators 32 and 33are pressured via lines 40, 41, 44 and 20 to the bottom of coal reactor10.

Carbon coated sand is withdrawn from the bottom of coal reactor 10 vialine 21 along with some cooling steam from line 24 and introduced intosand lock-bins 25 and 26. Additional carbon monoxide and hydrogen may beproduced by the injection of both steam and oxygen into the carbonatedsand or clay as it leaves the coal reactor. CO and H₂ are recovered byventing of the H₂ as a by-product. Steam may also be introduced intolock-bins 25 and 26 via line 126. The sand is steam pressured via lines27, 28 and 29 into sand decarbonizer beds 30 and 31. Air is pressuredcyclically via lines 52 and 53 to remove carbon from the sand at carbonmonoxide formation conditions. The sand with carbon removed, heated bythe exothermic carbon monoxide formation oxidation occurring withindecarbonizer beds 30 and 31, is steam pressured via lines 22 and 23 tocoal reactor 10.

Superimposed over the sand decarbonizers are hydrogen generator 32 and33 comprising fixed beds of ferrous metal reagent supported onperforated distributors 42 and 43.

In the ferrous metal reagent regeneration cycle, carbon monoxide formedby decarbonization is admitted upwardly through perforated distributors42 and 43 and through the metal reagent bed. The metal is reduced andthe resultant carbon dioxide and nitrogen exit via lines 36, 37 and 45to drive gas turbine 46 and air compressor 47. Heat is recovered fromthe hot carbon dioxide and nitrogen gases issuing from the metal reagentbeds and is used to generate steam in coils 34 and 35 prior to exitingvia lines 36 and 37. Additional heat may be recovered from the exitinggases in exchangers 48 and 49 prior to discharge as stack gas via duct50.

In the oxidation cycle steam from lines 38 and 39 reacts with thereduced ferrous metal reagent in fixed beds 32 and 33 to generate thehydrogen introduced into coal reactor 10 via line 20 in the mannerhereinbefore described.

The overhead from extractor tower 8 comprising diesel, gasoline and fuelgas vapors and steam is withdrawn via line 55, passed through cobaltdesulfurizers 56 and 57 and through sulfur disengager 58 to fractionator62. Elemental sulfur is recovered via line 59. Diesel oil is pumped fromthe bottom of fractionator 62 via line 64 to high pressure hydrogenator65. Recycle hydrogen via line 67 is introduced into hydrogenator 65 andis carried with hydrogenated oil via line 66 to the bottom of coalextractor 8. A portion of the diesel oil may be withdrawn as product vialine 97.

A gasoline fraction is withdrawn from fractionator 62 via line 110 tostripper 111 and withdrawn via line 112 as product. The overhead fromfractionator 62 is withdrawn via line 71 and coolers 69 and 72 toaccumulator 73. The hydrocarbon phase from accumulator 73 is refluxed toextinction via line 74 to the top of fractionator 62. The condensedwater phase in accumulator 73 is passed via line 75 to carbon dioxidestripper 89. From carbon dioxide stripper 89 the water via line 91 isintroduced into water treater 92 and thereafter recycled via lines 93,94 and 95 to separator 120, which is connected to steamgenerators/cooling coils 17, 34 and 35 by lines 123, 123', 124 and 125.Fuel gas is pressured via line 76 to carbon dioxide absorber 77 andwithdrawn as fuel gas product via line 70.

Regenerated caustic is passed from carbon dioxide stripper 89 via lines91 and 78 to the top of carbon dioxide absorber 77. Spend caustic isremoved from carbon dioxide absorber 77 via line 79 and passed to carbondioxide stripper 89 for regeneration thereof.

In ash decarbonizer 82, air from line 100 burns the carbon off the ash.Coarse ash accumulates in zone 83 and is withdrawn via duct 84 andsettles in settling zone 85 from which it is withdrawn as product vialine 95. Additional air, as required, may be introduced via line 86 toburn off additional carbon. A flue gas overhead is removed from zone 87via line 88 and introduced into carbon dioxide stripper 89 and withdrawnfrom stripper 89 via line 90 and through gas turbine 130.

Product steam may be recovered via line 140.

Air is introduced via line 98 and compressor 47 to start-up air heater51 and passed via line 150 to lines 86 and 100 feeding into ashdecarbonizer 82, line 151 feeding via line 20 into coal reactor 10 andlines 52 and 53 feeding into sand decarbonizers 30 and 31 respectively.

In accordance with the invention, the predominant part of coalconversion takes place within the coal reactor 10. Within the coalreactor hydrocracking of the coal-oil mixture is prominent to yieldgasoline, diesel oil vapors and higher BTU gases such as methane,ethane, etc. A particulate mixture of sand and an alloy of iron andchromium is maintained in the coal reactor. The mixture is comprised ofa minor portion of the particulate iron and chromium alloy and a majorportion of sand. More specifically, the particulate alloy is preferablypresent in an amount of about 10% by weight. The granular metal alloycontains from 5 to about 30%, by weight, chromium in order to avoid orminimize sintering of the metal granules and thereby to preventagglomeration with consequent reduction of surface area. The amount ofchromium may vary based on the composition of coal slag, which in turnvaries widely for different grades and forms of coal. In addition to theforegoing function, the chromium component of the iron alloy performsthe additional function of enhancing hydrocracking in the coal-oilreactor.

The particulate iron and chromium alloy employd in the present inventionpreferably contains from about 5 to 30 percent, by weight, chromium. Thechromium should be present in an amount of at least 2 percent to beeffective. The alloy may be a chromiumaustenite steel also containingother elements alloyed therewith such as nickel and cobalt. Theparticulate size of the alloy utilized in combination with sand as notedabove, is preferably within the range of from about 5 to about 500 mesh,the same size range as the sand. The particle size of the iron andchromium alloy used for the hydrogen generator may vary over an evenwider range, and for this purpose iron filings and shavings from machinelath operations are suitable.

The sand which is suitable for use in the instant process preferablyfalls within the range of from about 5 to about 500 mesh. The sandoperates to remove carbon formed in the coal reactor which is depositedon the sand, and the sand also provides a means of recovering the heatgenerated during combustion of the carbon to form carbon monoxide. Thesand, therefore, should be resistant to deterioration at the conditionsprevailing in the coal reactor and the carbon monoxide generator. The"sand" is also selected for high temperature resistance to coal slagsproduced by the variety of coal being processed. Examples of types ofsand suitable for use in the present invention are silicon dioxide,aluminum oxide and/or mixtures thereof, calcium, magnesium and/oraluminum silicate, fullers earth, or crushed refractory brickscontaining silica, alumina, chrome, magnesium oxide, iron oxide, ironsilicides, zirconium oxide, calcium oxide, silicon carbide and mixturesthereof.

Examples of clays suitable for use in the present invention are Georgiaattapulgas clays (Al₂ O₃. SiO₂), Florida clays (Al₂ O₃. SiO₂. CaO) andmulticomponent clays such as (Al₂ O₃. SiO₂. CaO.MgO) Georgia, Floridaand Texas clays or similar commercially available clays. The commercialclays are refined clays, from which foreign materials such as silt andheavy metals have been removed, and which have been calcined to removemoisture and crushed and screened to sizes of from about 5 to about 500mesh. The clay may contain an impregnate such as iron, nickel, cobalt,chromium, molybdenum or tungsten. The impregnate generally will bepresent in an amount of from about 0.05 wt.% to about 50 wt.% andpreferably about 0.1 to about 10% by wt. of the clay substrate.

It is preferred to the present invention to use clay in the coal reactorand in the chemical combustion hereinafter described. However, eithersand and/or clay may be used, and the terms "sand" and "clay" areemployed interchangeably.

Clay is preferred because it takes less fluidizing gases to maintain thefluidized bed and effect reaction therein. The sands tend to be denserthan their clay counterpart and, therefore, the retention time of thefluidizing agents, that is, oxygen, steam and/or hydrogen, is less in afluidizing bed of sand than in one of clay. Also, more fluidizing agentis regenerated when operating with sand than with the clay counterpart.Moreover, the density of certain clays is comparable to the coalfeedstock; therefore, homogeneous mixing is enhanced within thefluidized bed. Finally, clay, particularly fine clay of about 200 toabout 300 mesh, has an affinity for combining with alkali or alkalineearth metal compounds; therefore, use of clay has the added advantage ofeffecting removal of such detrimental metallic contaminants.

In the coal reactor the steam which is present reacts with a portion ofthe carbon to produce hydrogen and carbon monoxide as follows:

    C+H.sub.2 O→H.sub.2 +CO

Also in the coal reactor, the alloy reacts with the resulting carbonmonoxide and steam as follows:

    CO+FeO→Fe+CO.sub.2

    Fe+H.sub.2 O→H.sub.2 +FeO

Accordingly, a portion of the hydrogen for hydrocracking is formed insitu of the coal reactor. Methane formation also occurs in the coalreactor by dealkylation represented as follows:

    H.sub.2 +2RH-CH.sub.3 →2RH+2CH.sub.4

The lower molecular weight oil vapors containing gasoline and dieselfuels are produced by hydrocracking. As is readily appreciated, thereactions occurring in the reactor are both exothermic and endothermicin nature; however, it has been found that the constant addition of heatderived from circulating sand maintains the required elevatedtemperature and the reactions proceed quite rapidly.

It is also believed that when operating the coal reactor at elevatedtemperatures of from about 1000° F. to 1700° F. in the absence ofinjected oxygen, the organic oxygen contained in the coal or coal-oil isremoved from the coal macromolecule by reaction with the alloy asfollows:

    ROH+Fe→FeO+RH

    FeO+CO→Fe+CO.sub.2 +heat

This method of removing oxygen from coal is preferable to hydrogenconsuming organic oxygen removal with hydrogen represented as follows:

    ROH+H.sub.2 →H.sub.2 O+RH

One advantage of the present invention is that the fluidized bed of sandand alloy in the bottom portion of the coal reactor continuouslyoperates to transfer the heat generated during the formation of carbonmonoxide back to the coal reactor, thereby maintaining the coal-oilcracking temperatures and eliminating any requirements for oxygeninjection.

During coal conversion a carbon coating accumulates on the granular sandwithin the coal reactor. The sand is withdrawn from the coal reactor andthe carbon coating is removed by oxidation, generally with air. The sandoperates as a heat sump for said reaction allowing the obtaining of hightemperatures without initiation of afterburning. The resultant heatedsand is returned to the coal reactor to provide the heat requirementstherein. This cycling of sand serves two purposes; namely, providingheat for the coal reactor and carbon monoxide for the regeneration of ahydrogen generator. This generator is generally superimposed over thecarbon removal bed. Steam is passed, preferably, downwardly through thegenerator to form hydrogen. The simplicity of operation is at onceapparent. The heat of formation of carbon monoxide is returned to thecoal reactor by recycling of regenerated sands and alloy, and the heatof formation of carbon monoxide to carbon dioxide is retained by the bedof iron and chromium alloy to provide the heat of formation of hydrogenas well as to impart additional heat to the steam and hydrogen productstream which issues from the hydrogenator and is introduced into thecoal reactor. As a result of this sequential oxidation, localoverheating caused by afterburning in the lower fluidized sand bed isavoided and the heat of combustion is recovered in a most efficientmanner. Moreover, this procedure allows for complete combustion, therebyavoiding emission of carbon monoxide into the atmosphere.

In the coal reactor the carbon retained on the ash may be removed byintroducing additional steam into the annular ash accumulator, and anyresidual carbon yet remaining on the ash may be removed after withdrawalof the ash from the coal reactor in an external air burner.

The oil vapor and fuel gas treatment downstream of the coal reactorgenerally includes cooling, and preferbly includes heat exchange in theupper portion of the coal reactor to form steam prior to introductioninto an oil extractor tower.

A vaporous overhead containing hydrocarbon fractions in the gasoline anddiesel range and lighter fuel gases is withdrawn from the coaloil-extractor, desulfurized, if necessary, and fractionated. Fuel gasand gasoline fractions are recovered as product and at least a portionof the diesel oil is hydrogenated to enhance its hydrogen content andrecycled to the coal oil extractor and reactor.

EXAMPLE

A change of Illinois coal containing about 4% sulfur is ground to 100mesh and finer. Sand and/or clay granules within the size range of 10 to50 mesh and chromium containing steel alloy granules within the sizerange of 10 to 80 mesh are admixed in proportions to provide a 10% byweight blend of alloy granules in sand. For the chromium-containingsteel alloy in the hydrogenator, metal chips 1/8 to 1/2 inch in diameterare employed. The alloy used in the sand blend and the fixed bed of thehydrogenator is a 430 ferritic steel containing about 16% chromium.

The coal charge is fed to the coal reactor at the rate of 100 lbs./hr.The coal reactor is operated at a temperature of from about 1200° F. toabout 1700° F. and a pressure of about 500 psig. The hydrogenator isoperated at a pressure of about 1000 psig and a temperature of fromabout 750° F. to about 950° F. The temperature within the sanddecarbonizer is from about 1300° F. to about 1800° F., and the sand andalloy withdrawn from the sand decarbonizer and fed to the coal reactoris at a temperature of from about 1500° F. to about 1700° F. The dieselproduct is recycled to extinction and 72% of the coal value is recoveredas follows:

    ______________________________________                                        Gasoline Product    30% of coal value                                         Industrial Hydrogen 20% of coal value                                         Methane Plus Gases  22% of coal value                                         ______________________________________                                    

Another aspect of the invention is illustrated by FIG. 2. The processillustrated in FIG. 2 places emphasis on electricity production.

Coal feed in particulate form and preferably 1/4 inch or less indiameter is charged via line 201 into lock-bins 202 and 203. The coalmay be partially dried, but should have a moisture content of from about5 to about 20% by weight. The coal is air pressured and/or augeredthrough piping system 204 to the bottom zone of coal reactor 205. Thecoal is injected into a fluidized bed of clay, which clay preferablycontains a catalytic metallic component for catalysis of coalconversion. The clay is preferably an attapulgas clay, suitably Georgiatype attapulgas clay, impregnated with a tungsten coating. Uponinjection into fluidized clay bed 206, the coal particles aredisintegrated by the transformation of the moisture contained within thecoal to steam. This transformation is a result of coal particle contactwith the hot fluidized clay bed 206.

Steam 207 and air 208 are injected through bottom distributor plate 209,and the coal is rapidly, within a few seconds, converted to gaseousfuels including hydrogen, carbon monoxide, methane, ethane, ethylene,propane, etc. Concurrently, powdered ash residue resulting from the coalconversion is blown upward via area restricted central duct 210. Thepowdered ash residue settles out in ash accumulator 211. The ash maythen be decarbonized by air and steam injection via lines 212 and 213respectively, and the ash product is withdrawn via line 214 to storage.

The carbon content of the ash may be retained thereon. Indeed conditionsmay be adjusted to obtain ash carbon content of from about 10% weight toabout 80% weight, such high carbon content ash being suitable for drypipelining to chemical plants. Where high carbon content is desired, theprocess is operated at a high coal ratio to produce a carbonated ashproduct containing from about 10% weight to about 80% weight carbon.

A unique feature of the present invention is that the ascending fuelvapor product is treated within the upper portion of the reactor. Thefuel vapors pass upwardly into reactor zone 216 via restricted centralduct 215, which duct is perforated, and preferably controlled with thebase forming the fuel vapor inlet. Calcium oxide, dolomite (CaCO₃.MgCO₃) or equivalents thereof are injected into reactor zone 216 andreact with hydrogen sulfide which is present in the fuel gas to formcalcium sulfide as represented below:

    CaO+H.sub.2 S→CaS+H.sub.2 O

Chlorine which is present in the fuel gas also reacts with calcium oxideto form calcium chloride as follows:

    CaO+2HC1→CaCl.sub.2 +H.sub.2 O

The calcium sulfide and calcium chloride so formed flow upwardly intoreactor zone 217 and settle in annular chamber 218. Calcium sulfide andcalcium chloride are withdrawn as a byproduct via line 219. The denserCaO which remains unreacted accumulates in annular chamber 220encircling restricted control conduit 215 and may be withdrawn andrecycled. Specific gravities of the calcium salts are as follows:

    ______________________________________                                                        Specific Gravity                                              ______________________________________                                        CaS               2.18                                                        CaCl.sub.2        2.51                                                        CaO                3.346                                                      ______________________________________                                    

The gaseous overhead fuel product is cooled by steam generator coil 221.The gaseous product and any remaining excess steam are pressured vialine 222 to oil absorber tower 223.

In oil absorber tower 223, the condensed liquid product comprising themiddle distillate diesel oil fraction is circulated via line 224. Theentrained solids carried over into oil absorber tower 223 accumulate inthe heavy oil recycle and are returned to the coal reactor via line 225.Accordingly, solid removal is effected substantially via ash draw line214. A distilled oil product may be withdrawn via line 226. A portion ofthe fuel gas may be recovered as product via lines 228, and theremainder may be fed via line 229 to chemical combustor 230.

In chemical combustor 230, the fuel gas is burned by contact of the fuelwith a fluidized bed of metal-impregnated clay denoted by number 231.Contact is effected at a temperature of from about 1500° F. to about2000° F. and preferably about 1800° F. to about 2000° F. Air isintroduced into combustor 230 via line 232, and steam is introduced intocombuster 230 via line 233. Substantially complete combustion of thefuel gas is effected, preferably utilizing air in substantially astoichiometric amount. Air containing oxygen in excess of thestoichiometric amount required to effect complete combustion of the fuelgas may be used; however, the use of insufficient air will result inincomplete combustion with attendent energy loss and decrease in theefficiency of the overall process. Steam generator coil 234 is operatedto maintain the combution temperature at about 2000° F. or less in orderto minimize nitrogen oxide emissions. The metal impregnated claypreferably comprises a clay, selected from the group consisting of iron,iron-chromium alloy, iron-chromium-nickel alloy, cobalt, cobaltsilicide, iron-silicide or materials of similar reactivity, and themetal impregnate is preferable selected from the group consisting oftungsten and similarly reactive high melting heavy metals.

The particle size of the metal-impregnated clay may vary from about 15mesh to about 100 mesh.

Where the preferred metal impregnate, tungsten, is utilized in combustor230, the particles containing tungsten in oxide form are concentrated atthe upper portion of the fluidized bed. The tungsten oxide component ofthe particles provides oxygen for combustion of fuel gas. Uponreduction, the metallic tungsten-coated particles gravitate to thebottom of the fluidized bed where they are oxidized. The oxidizedparticles migrate to the upper portion of the fluidized bed to repeatthe sequence. The recirculation of particles is a consequence ofdiffering specific gravities. Tungsten metal has a specific gravity of19.3; the trioxide form of tungsten has a gravity of 7.16, and thedioxide forms of tungsten has a specific gravity of 12.0. Since tungstenoxidizes readily at the combustion temperature maintained withincombustor 230 (namely, from about 1800° F. to 2000° F.), fuel combustionis readily maintained at an efficient level, even in the presence ofexcess cooling steam. The velocity of the fluidizing gases is adjustedin a manner well known in the art to obviate solid entrainment in theexiting gases. In the event of solid entrainment, the tortuous path ofthe exiting gases formed by a baffle arrangement such as illustrated bybaffles 235 and 236 permits recovery of such entrained solids andwithdrawal via side bottom drain line 237. The combustor mayconveniently be encased for cooling purposes within a water-jacket.Cooling effected by heat exchange in the foregoing manner is employed tomaintain combustion gases exiting via line 250 at temperatures withinthe range of from about 1500° F. to about 2400° F. and preferably forabout 1800° F. to about 2000° F. to prevent injuring the blades ofturbine 260.

The combustion gases via line 250 drive gas turbine 260 which in turndrives air compressor 270 and electric generator 280.

EXAMPLE

An example of a pilot plant operation performance run is shown below:

    ______________________________________                                        Coal charge (Illinois coal)   100 lbs./hr.                                    Fuel gas product  % coal energy                                               carbon monoxide   10%                                                         methane           18                                                          ethane            5                                                           ethylene          6                                                           propane           3                                                           hydrogen          28                                                                            70                                                          Reactor pressure              500 p.s.i.g.                                    Reactor temperatures                                                          bottom zone                   1550° F.                                 top zone                      815° F.                                  Cobalt treater temperature    810° F.                                  Combustor temperatures                                                        prior to steam quench         1910° F.                                 after steam quench            1540° F.                                 ______________________________________                                    

The clay utilized in the coal reactor is 30 to 60 mesh Attapulgas clayimpregnated with 0.15% by weight tungsten. The clay utilized in thecombustor is 20 to 50 mesh Florida clay impregnated with 0.25% by weighttungsten. 300 mesh Georgia clay in an amount of about 0.01% by weightbased on coal feed, is injected into the coal reactor along with thecoal feed in order to neutralize the sodium in the coal ash. This clayis removed with the ash product. The transformation of coal toelectricity has a thermal efficiency of 50% to 55%.

FIG. 3 represents yet another aspect of the invention, combining thecoal reaction scheme described in FIG. 2 with municipal solid wastetreatment to recover fuel values therefrom and produce electricity. Thefeature CaO treatment may be omitted in the combined coal and municipalwaste conversion method illustrated in FIG. 3, in which event othermeans of desulfurization are preferably employed.

Coal feed in particulate form and preferably 1/4 inch or less indiameter is charged into lock-bins 302 and 303 via line 301. The coalmay be partially dried, but should preferably contain a moisture contentof from about 1% weight to about 20% weight. The coal is air pressuredand/or augered through pipe systems 304 and 305 into a fluidized bed ofclay in the manner and under the conditions heretofor described inconnecting with the process described in FIG. 2. Steam 306 and air 307are injected through bottom distributor plate 308 into coal reactor 315,and the coal is rapidly, within a few seconds, converted to gaseousfuels. The gaseous fuels at the elevated temperatures of production arewithdrawn overhead via line 309. Concurrently, the powdered ash residueresulting from the coal conversion is blown upward via area restrictedcentral duct 310 to then settle out in ash accumulator 311, an annularchamber defined by the outer wall of coal reactor 315 and central duct310. The ash product is discharged via line 312.

Solid wastes, for example, residential home solid wastes, are introducedvia line 321 into multiple lock-bins 322 and 323. When the lock-bins arefilled, hot coal producer gases via lines 309 and 325 are fed into thebottom of the solid waste filled lock-bins at a temperature of fromabout 700° F. to about 1000° F. to rapidly heat the solid wastes. Airfrom line 335 and steam from lines 336 and 337 are introduced into thebottom portion of lock-bins 322 and 323 to gasify the solid wastes. Whenthe combustible portion of the solid wastes has been gasified, theresidual inorganic portion is withdrawn via lines 338, 339 and 340. Thegasified portion of the solid wastes is pressured from the top oflock-bins 322 and 323 via lines 341 and 342 respectively. A portion ofthe coal producer gas from line 309 via lines 343 and 344 may be used totemperature quench the gasified solid waste producer gas.

The combined producer gases from the coal reactor and solid wasteconverters are pressured via line 345 into cobalt desulfurization unit346. Sulfur is recovered via line 347. Desulfurized fuel gases arewithdrawn from the desulfurizer via line 348. A portion of the fuelgases may be recovered via line 349. At least a portion of thedesulfurized fuel gases are introduced via line 350 into combustor 355.Combustor 355 is operated in the same manner as combustor 230. Thecombustion gases are withdrawn from combustor 355 via line 356 to drivegas turbine 360 which in turn drives air compressor 370 and electricgenerator 380.

The steam utilized in the process may be generated in steam generators390 and 391.

EXAMPLE

An example of the pilot plant operation parameters is set forth below:

    ______________________________________                                        Solid waste charge    200 lbs./hr.                                            Coal charge           10 lbs./hr.                                             Coal reactor pressure 520 p.s.i.g.                                            Solid waste reactor pressure                                                                        500 p.s.i.g.                                            Solid waste reactor temperature                                                                     1750° F.                                         Solid waste reactor inorganic yield                                                                 20% by weight                                           Combustor bed temperature                                                                           1875° F.                                         Solid waste to electric thermal                                                                     50% by weight                                           efficiency                                                                    ______________________________________                                    

The type of solid organic waste materials suitable for conversion toliquid and gaseous fuels are well known. Organic waste materials mostsuitable for this invention are those materials cellulosic in naturesuch as ground paper, sawdust or ground leaves. Also suitable are otherresidential waste materials such as waste food materials and usedclothing, etc. Industrial wastes which are organic in nature are alsosuitable and, in this regard, rubber tires may be converted inaccordance with this process.

Residential waste when collected generally contains glass, iron, dirtand other inorganic components; therefore, removal of at least a portionof such materials prior to conversion in accordance with this process isdesirable. This can be accomplished routinely by first running the wastematerial through a hammermill to obtain particles of 6 inch or lessdiameter. Thereafter the iron components of the waste may be removed bymagnetic drum. The remainder of the waste material is changed to theconversion chambers 322 and 323 heretofor described to effectgasification of the solid organic component with the hot fuel gasproduct derived from the coal conversion step of this invention. Theprocess can be adapted for either cyclic or continuous waste feed. Thenon-converted waste component is removed from the bottom of multiplelock-bins 322 and 323.

In a general manner, while there has been disclosed an effective andefficient embodiment of the invention, it should be well understood thatthe invention is not limited to such an embodiment as there might bechanges made in the arrangement, disposition, and form of the partswithout departing from the principle of the present invention ascomprehended within the scope of the accompanying claims.

What I claim is:
 1. A method of converting coal to liquid and gaseousfuels comprising the steps of:(a) introducing coal having a moisturecontent of from about 10 wt. % to about 30 wt. % into a verticallyelongated coal reactor having a fluidized bed of sand and/or clay in thebottom portion thereof; (b) introducing superheated hydrogen at atemperature of from about 1000° F. to about 1800° F. into the bottom ofsaid coal reactor; (c) transforming said moisture to steam todisintegrate said coal; and (d) converting said disintegrated coal at atemperature from about 1200° F. to about 1700° F. to liquid and gaseousfuels comprising carbon monoxide and hydrogen.
 2. The method of claim 1wherein the coal has a moisture content of from about 10 wt. % to about20 wt. %.
 3. The method of claim 1 wherein said fluidized bed is ofAttapulgas-type clay.
 4. The method of claim 1 and further comprisingthe step of introducing superheated steam into the bottom of said coalreactor.
 5. The method of claim 1 further characterized in thatfluidization of said fluidized bed is effected with air, steam andgaseous fuel product recovered overhead from the coal reaction.
 6. Themethod of claim 3 further characterized in that said clay contains ametallic catalytic component.
 7. The method of claim 6 furthercharacterized in that said clay contains a tungsten impregnate.
 8. Themethod of claim 3 wherein said fluidized bed is of Attapulgas-type clay.9. The method of claim 1, wherein the coal has a moisture content ofabout 20 wt. %.
 10. A method of converting coal to liquid and gaseousfuels comprising the steps of:(a) introducing coal having a moisturecontent of from about 6 wt. % to about 30 wt. % into a verticallyelongated coal reactor having a fluidized bed of sand and/or clay in thebottom portion thereof; (b) introducing superheated steam at atemperature of from about 1000° F. to about 1800° F. into the bottom ofsaid coal reactor; (c) transforming said moisture to steam todisintegrate said coal; and (d) converting said disintegrated coal at atemperature from about 1200° F. to about 1700° F. to liquid and gaseousfuels comprising carbon monoxide and hydrogen.
 11. The method of claim10 further characterized in that fluidization of said fluidized bed iseffected with air, steam and gaseous fuel product recovered overheadfrom the coal reaction.
 12. The method of claim 1 wherein the coal has amoisture content of from about 10 wt. % to about 20 wt. %.
 13. Themethod of claim 10 further characterized in that said clay contains ametallic catalytic component.
 14. The method of claim 13 furthercharacterized in that said clay contains a tungsten impregnate.
 15. Themethod of claim 10, wherein the coal has a moisture content of about 20wt. %.